Actual lab benches kinda vary in material, some being stainless steel and some being various other fairly inert materials. They're also going to be expensive as hell, new or used. I have no idea about "medical" stuff.

You might be able to find stuff cheaper if there's a local auction place or flea market near you that sells surplus business or government stuff. You could also look for stainless steel or aluminum furniture among the usual online vendors, I've seen polished aluminum furniture in places that was made to look fancier than it actually was.

Edit: If you just wanted to take a picture of something on a metal table… Chipotle?

In chemistry labs, popular surface types include sealed & polished stone, stainless steel, and epoxy- basically things that you can spill concentrated sulfuric acid on without needing to panic about it.